海工耐久混凝土氯离子渗透性能的影响因素及其扩散系数的早期推定

大规模海工耐久混凝土在国内应用很少,各种影响因素对其影响作用不甚明了,通过正交设计的方法研究各影响因素对耐久性的影响,对指导配合比设计和施工过程质量控制具有积极的意义。     

机车空调逆变电源控制系统及其实现

根据机车空调电源的特点,设计了满足机车空调电源应用要求的逆变器控制系统,包括逆变器电路组成、工作原理、控制系统硬件及软件等,突出了系统变频运行、智能控制等特点.设计方案得到了试验证实,设计样机满足运用要求.     

Ramp meters on trial: Evidence from the Twin Cities metering holiday

Ramp meters in the Twin Cities have been the subject of a recent test of their effectiveness, involving turning them off for eight weeks. This paper analyzes the results with and without ramp metering for several representative freeways during the afternoon peak period. Seven performance measures: mobility, equity, productivity, consumers’ surplus, accessibility, travel time variation and travel demand responses are compared. It is found that ramp meters are particularly helpful for long trips relative to short trips. Ramp metering, while generally beneficial to freeway segments, may not improve trip travel times (including ramp delays). The reduction in travel time variation comprises another benefit from ramp meters. Non-work trips and work trips respond differently to ramp meters. The results are mixed, suggesting a more refined ramp control algorithm, which explicitly considers ramp delay, is in order.     

A review of the Effect of α/W ratio on fracture toughness （Ⅱ） experimental investigation in LEFM

In part I of this series, experimental investigation in EPFM （elastic-plastic fracture mechanics） had been discussed. In this paper, experimental investigation in LEFM （ linear elastic fracture mechanics） is given. Fracture toughness tests had been carried out on three different strength steels, using both through-cracked specimens with different α/W ratio and semi-elliptical cracked specimens with variable crack size and shape. Results show that the fracture toughness KIC increases with decreasing α/W when α/W 〈 0.3 for three-point-bend specimens, and that for α/W 〉 0.3, it is independent of α/W. Shallow crack specimens, both through-cracked and surface-cracked, gave markedly higher values than deeply notched specimens. However, the effect of crack shape on fracture toughness is negligible. Results also show that the LEFM approach to fracture is not tenable for design stresses where αc is often very small, far less than 2.5 （ KIC/σy）^2.     

锚喷支护设计专家系统的研究

锚喷支护设计专家系统（ＰＴＥＳ）是在广泛收集国内外锚喷支护设计的理论知识和广大支护专家群体丰富设计经验的基础上，结合国家标准锚喷支护设计规范，应用专家系统技术研制而成的。它是一个以人－机对话为主，具有多模块、多功能的智能化程序设计软件。它能模仿人类专家的思维方式和思维过程，最终根据工程类型、地质条件、围岩类别、工程断面形状和尺寸等因素确定工程的支护形式和支护参数。     

盾构在小半径曲线下穿越建筑物的施工技术

随着盾构法施工在城市地铁隧道中的应用,使得在盾构法施工中面临到的环境也越来越复杂.以上海市12号线东兰路站～虹梅路站区间隧道为工程实例,介绍了一些在盾构施工中面临小半径曲线下穿越建筑物的施工技术,对在施工过程中遇到的难点、重点进行了分析,提出了一些解决方法,对以后类似工程有一定的借鉴作用.     

CRH380CL新一代高速动车组制动系统研制

介绍了CRH380CL新一代高速动车组的制动系统,重点阐述了制动系统结构、功能原理、设计计算和试验等内容。     

板式无砟轨道水泥乳化沥青砂浆施工质量控制技术

通过宁杭高铁水泥乳化沥青砂浆的施工实例,分析了水泥乳化沥青砂浆的原材料、配合比以及润湿、封边、灌浆、养护等工艺对施工质量的影响,重点阐述了各阶段施工质量控制要点,提出了相应的质量控制措施.     

CRH2-300动车组制动摩擦系数优化试验研究

对CRH2-300型动车组制动减速度试验情况和摩擦系数利用优化方案作了介绍。对武广客运专线进行的摩擦系数利用方案试验结果进行了分析和总结,并与原方案试验结果进行了对比。试验结果表明,摩擦系数优化方案可行。     

岩石地区地铁矿山法区间 隧道衬砌设计模式

岩石地区地铁矿山法区间隧道衬砌的设计模式长期处于无章可循的状态,亟须合理化、规范化。从结构可靠度的角度出发,分3种模式(铁规破损阶段法、铁规概率极限状态法、建规概率极限状态法)对铁路系统和建工系统的设计模式进行分析研究,提出合理的可靠度设计方法进行P-Δ分析,并提出区间隧道设计中各个关键参数的合理取值。